wip: abstract stack/continuation machine

2026-08-17 22:31:45 -06:00
parent c3c4866fa8
commit 745277ed1a
16 changed files with 723 additions and 22 deletions
@@ -0,0 +1,83 @@
+#+title: closure-conversion
+
+the closure-conversion phase makes closed-over variables explicit by addition of the primitive ~make-closure~, taking a code pointer (in the CPS language, bare lambda) and the environment.
+
+* scratchpad
+
+#+begin_src scheme
+(letrec ((make-adder
+        (lambda (n)
+          (lambda (x)
+            (+ n x)))))
+((make-adder 3) 2))
+#+end_src
+
+#+begin_src scheme
+(define add-code
+  (lambda (n env)
+    (+ n (env-ref env 'x))))
+
+(define make-adder-code
+  (lambda (n)
+    (make-closure add-code ('x n))))
+
+(define make-adder (make-closure make-adder-code))
+
+(apply-closure (apply-closure make-addder 3) 2)
+#+end_src
+
+#+begin_src wat
+(module
+ (type $heap-object (sub (struct (field $hash (mut i32)))))
+ (type $closure (sub $heap-object
+                     (struct (field $hash (mut i32))
+                             (field $code (ref $cont-type)))))
+ (type $closure1 (sub $closure
+                      (struct (field $hash (mut i32))
+                              (field $code (ref $cont-type))
+                              (field $env0 (ref eq)))))
+ (global $arg0 (mut (ref null eq)) (ref.null eq))
+ (global $arg1 (mut (ref null eq)) (ref.null eq))
+ (global $arg2 (mut (ref null eq)) (ref.null eq))
+ (global $arg3 (mut (ref null eq)) (ref.null eq))
+ (global $arg4 (mut (ref null eq)) (ref.null eq))
+ (global $arg5 (mut (ref null eq)) (ref.null eq))
+ ;; ⋮
+ ;; (global $argn (mut (ref null eq)) (ref.null eq))
+
+ (global $current-closure (mut (ref null $closure)) (ref.null $closure))
+
+ (func $add-code (param $nargs i32)
+       (local $n (ref eq))
+       (local $x (ref eq))
+       (local.set $n (global.get $arg0))
+       (local.set $x (struct.get $closure1
+                                 (global.get $current-closure)
+                                 $env0))
+       (return (i32.add $n $x)))
+
+ (func $make-adder-code (param $nargs i32)
+       (local $n (ref eq))
+       (local.set $n (global.get $arg0))
+       (return (struct.new $closure1
+                           0
+                           $add-code)))
+
+ (func $main
+       (local.set $make-adder
+                  (struct.new $closure
+                              0
+                              $make-adder-code))
+       (global.set $current-closure $make-adder)
+       (global.set $arg0 (i32.const 3))
+       (local.set $f (call (struct.get $closure
+                                       $make-adder
+                                       $code)
+                           1))
+       (global.set $current-closure $f)
+       (global.set $arg0 (i32.const 2))
+       (return (call (struct.get $closure
+                                 $f
+                                 $code)
+                     1))))
+#+end_src